Recovery of oil from tar sands and other oil-bearing formations



Oct. 22, 1963 H. RECOVERY OF Filed Feb. 3. 1961 Process Applied t o 95] Recovery it Wells inject Caustic-Surfactant Solution in injection Wall Add H 50 to pH 5 Collect Produce Emulsion 9 Oil c Produced to Produce Emulsion mom a Producflon Wall Underground Add Make-up Ga (on) Mum Solution Add Make-up Surfactant Remove 56PM"3 Add NoOH ca Produced Ca(OH) Note If an acid-base system is used such that the sail formed ls water-soluble, the stops corresponding to discarding Co$0 and adding NoOH may be "ellminatad. Examples of other alkaline materials which may be mad are NaOH, KOH, NH OH, 66 00 numerous amines. Also, in lieuot H 30 any other acid, inorganic or organic, or oven acid salts may be used.

United States Patent O 3,107,726 RECOVERY OF OIL FROM TAR SANDS AND OTHER OIL-BEARING FORMATIONS Harold L. Greenwald, Levittown, Pm, assignor to Rohm 8: Haas Company, Philadelphia, Pa., a corporation of Delaware Filed Feb. 3, 1961, Ser. No. 87,041 2 Claims. (Cl. 166-8) This is a continuation-in-part of application Serial Number 760,935, filed on September 15, 1958.

This invention relates to a novel method for separating and recovering oil from tar sands and other oil-bearing formations. It particularly pertains to methods for recovering oil employing a well-flooding operation using an aqueous surfactant solution, and is especially significant because it also provides for the reclamation and re-use of the surfactant.

Broadly stated, the object of my invention is to provide an efiicient method for effecting the recovery of oil by a type of water-flooding operation in which an aqueous surfactant solution is employed to accomplish the oil recovery, and for recovering and re-using most of the surfactant so used.

Another object is to provide a process for the recovery of oil by the use of an aqueous surfactant solution which causes an oil-water emulsion to be produced, said emulsion being readily and inexpensively broken so that the surfactant canbe efficiently recovered in a single phase and re-used and the oils economically obtained.

Other objects of the invention, together with some of the advantageous features thereof, will appear from the following description and specification. In most cases, recovery of the surfactant will be a principal feature; however, the invention is not necessarily limited thereto as in certain applications it will be useful only to emulsify and demulsify in accordance with the novel methods herein described. H

Many agents have been proposed for emulsifying and demulsifying oils. But in certain applications, notably In my process, when stability of the emulsion is rendered a minimum, recovery of the surfactant for reuse is facilitated either by preferential solubility of the surfactant in the organic or the aqueous phase or by precipitation of the surfactant. My invention may thus be practiced in three alternative procedures which may conveniently begrouped as follows:

CATEGORY A (1) Make oil-water emulsion by means of a surfactant 2) Recover surfactant in aqueous phase by suitable control of pH in both steps CATEGORY B (1) Make oil-water emulsion by means of a surfactant (2) Recover surfactant in organic phase by suitable control of pH in both steps CATEGORY C (1) Make oil-water emulsion by means of a surfactant (2) Recover surfactant as a precipitate by suitable control of pH in both steps of the surfactant in one bulk phase or the'other as I choose. This choice is made dependent on the contemplated mode of reuse of the surfactant or of the surfactant as a separate, pure-or almost purephase for convenience in reuse. This ability to concentrate, in one M phase, a good emulsifier which otherwise is spread over in the recovery of oil from various unusual petroleumbearing formations, such as tar sands, these agents have PI'OVCII unsatisfactory for one reason or another. Among the principal objections are the use of relatively costly emulsifying materials which are substantially non-recoverable, the difiiculty in forming the emulsions, the difficulty in breaking the emulsions, etc.

The present invention overcomes all of these objections by the novel use of certain surfactants in emulsification-dernulsification procedures which make possible alkaline. In actual practice, it may be desirable in some cases to effect a closer control of the acidity or alkalinity of the treated solution in order to maximize the recovery of surfactant. This variation of pH enectively controls emulsion stability and the concentration of the surfaceactive agent in each phase.

three locations as above explained, is a novel as well as highly useful feature of my invention.

"Examples of Process Employing Single Cycle Not all surfactants will work in my novel process and, of those that do work, not all of them will function satisfactorily in each of the three categories described above. The selection and manner of employment of the various surfactants are, therefore, important to the successful practice of the invention. In essence, it may be stated that any surfactant having weakly acidic or weakly basic groups will work in one or more of the systems encompassed by my invention. The surfactants which will not work efficiently are those whose hydrophilic por-' tion is entirely (a) nonionic, or (b) composed of the anion of a strong acid or of the cation of a strong base.

In the numerous examples which were conducted to demonstrate the operation of the invention, the starting solutionsemployed were divided into two main sets. One set was a 0.5 percent solution of the surfactant in 0.5 percent NaOH, and the other set was a 0.5 percent solution of the surfactant in 0.5 percent H 80 However, in order to demonstrate effectiveness at different concentrations, several experiments were run in which the initial surfactant concentration ranged from 0.05 to 20 percent.

Equal volumes of the oil and of the surfactant-caustic or of the surfactant-acid solution (as the case may he) were placed in each of the two screw-cap jars and agitated time the volumes of the various phases were recorded and the percent recovery of the aqueous phase (a messstability in the second jar. .The emulsion instability one hour after adding the acid or base was computed and reported as the percent recovery of the aqueous phase.

For any surfactant having weakly acidic or weakly basic groups, oil-water systems will be found in which my invention will operate eilic-iently. Conversely, for

any given oil-water system, surfactants of this type exist which will work eiliciently. It is wellknown in the art that the hydrophilic-lipophile balance of an emulsifier determines its effectiveness for a given oil-water system.

Thus, the well-known techniques for choosing a good emulsifier are to be applied to the classes containing weakly acidic or weakly basic groups as a preliminary step in the practice of my invention. This was done as described in the following paragraphs.

All the tests were conducted at room temperature. The pH was checked at two or more points in each case. The surfactants which formed a relatively stable emulsion in base were deemed to be useful in the processes of all three categories, A, B, and C, previously described, particinarly the processes in which the oil was emulsified in base and broken with acid. High, low, or moderate recovery of the surfactant in aqueous phase determined whether the surfactant belonged in category A or B or failed to qualify. it a high percentage of the surfactant precipitated upon acidification, the surfactant qualified for category C. The same principles were used in determining the utility of surfactants for the processes in each of the three categories in which the oil was emulsified in acid and broken with base, except that the direction along 10 the pH scale was reversed.

The above-described tests involve a single cycle process, and the data obtained thereby are represented in Tables 1, 2, 3 and 4. Other experiments were run with a recycling process, which will be described in detail below, and the data obtained thereby are represented in Tables 5, 6 and 7. in almost all of the examples, the oils used were toluene and Ventura" crude oil (a relatively clean crude oil). Six other oils (is. organic liquids which are insoluble in water) were used to test the efficiency of the invention under various conditions making a. total of eight as follows:

(1) Toluene (2) Ventura crude oil (3) Howard Glasscock crude oil (4) Hawkins Field crude oil (5) Wesson oil (cottonseed oil) (6) Di-butylsebaoate (7) Di-octyl sebacate (8) Mixture of lauryl and myristyl alcohols.

No'rn.Nos. 2, 3 and 4 represent oils that are wellknown by those names to persons familiar with the petroleum field.

N0. 5 is a well-known eommerctalproduct sold under that:

name. No. 8 is a. commercially available mixture sold under a tradenarne.

The results obtained with the single cycle process are set forth in Tables 1 to 4.

- TABLE 1.EMULSIFIED IN CAUB'IIC BROKEN IYVI'IH ACID; SURFACTANTRECOVERED m A urioUs PEAS {Organic phase: Toluene. Aqueous phase: Surfactant, 0.5% NsOH, delonizedHiO (all pH's:12.8-l3.l)]

Surfactant Mole ratio conc. tn Emulsion pH s after Emulsion A-nercent B-percent Burractant of weight! instability acldlfiinstability of i. O. of of I. G. or A-i-B d EO(n) I volume in caustic cation after acidsurfactant surfactant percent ttlcatlon in aqueous. in toluene (I. C.) b

10.0 p 0.5 36 3-4 102 98 3 101 12.8 0.6 102 15.0 0.05 as a c 1 r 15.0 0.5 22 2-3 100 100 1 100 16.0 5.0 18 4 101 89 0 89 20.0 0.5 32 2 l 101 98 1 99 20.0 20.0 0 l 5 103 101 1 102 30. 0 0. 5 30 2-5 103 101 3 104 3 0.5 61 4 101 78 42 15 0.5 M 3 0 101 00 2 98 20 0.6 l! 2 8 I 71' 94 2 96 NOTES ON TABLE 1 (l) Surfactants Nos. 1 to 8 were ethylene oxide sdducts of a commercial product comprising a mixture of amines which prlnclpally covers the range 0! Cu u -H: 0 u ::N the number M hyl Oxide units P amine being from 10 to 30.

(2) Surfactants Nos. 9 and 10 were each the sodium salt 0! the sulfated ethylene oxide adducts of the type referred to in note (1) above.

(3) Surfactant N o. 11 was a commercially available product, a dehydroabletylamlne ethylene oxide adduct 7 with the structure in which 2411-20.

I WW-number of units of ethylene oxide, including the ethanol termination, in the. polyether chain. h I.C.=lnltlsl coneentratlon of surfactant expressed as welght/volume percent.

A single result such as 3 or 3.0 denotes that all 0! the data were taken for this one pair of emulsions. Where a range ls lndlcarod, such as 2-4, one or them (the 2 or the 4) was a repeat. The figures not reported to a tenth of a pH unit were determined by using pH test papers; the other figures were obtained with a pH meter.

d A+B should equal 100 percent or complete amountabillty of the surfactant. Q Result obtained was greater than 100 percent due to llmltatlons of method of analysts caused by the low concentration 0! the surfactant.

3,107,726 5 5 Tblc 1 contains data comparing various sub in which only toluene was employed, Table 2 which follows compared surfactants in the process as applied to faetauts an an enmlsifioauon-demulsification system various other OHS.

TABLE 2.EMULSIFIED IN CAUSTIC, BROKEN WITH ACID; SURFACTANT RECOVERED IN AQUEOUS PHASE [Organic phue: Various oils listed. Aqueous phase: Surfactant, 0.5% NaOH, deionized H O] Suriactant Emulsion cone. in Emulsion pH- after instability Percent of Surfac- Mole ratio welght/ Oil used instability acldlflcaafter LC. of

taut of EO(n) vol me in caustic tion acldlfleasurfactant percent tion in aqueous (1.0-) b 12. 6 0. 5 Ventura. crude oil 56 6. 6 90 15. 0. d0 4 3-4 96 15. 0 0. 5 44 3. 4 98 99 15. 0 5. 0 8 3. 0 100 93 20. 0 D. 5 40 4. 0-4. 5 101 20. 0 20. 0 0 1. 4 95 30. D 0. 5 40 2. 4-4 100 O. 5 22 4. 0 75 15 0. 5 54 2. 6 100 0. 5 62 2. 5 96 15 0. 5 44 2. 9 100 0. 5 60-70 2 93 20 0.5 do 46 2.6 98 15 0. 5 Howard Glasscock- 59 2-3 99 96 15 0.5 Hawk. Field. 53 2-3 97 89 20 0. 6 Wesson oil- 79 2 20 5.0 do 50 2 94 98 20 0. 6 Mixture of lauryl and 0 2. 1 0-32 myristyl alcohols.

NOTES ON TABLE 2 (1) Surfactants Nos. 1 to 7 and 14 to 17 were the same as described in note (1) in Table 1. (2) Surfactant No. 8 was the same as described in note (2) in Table 1. (3) Surfactants Nos. 9 and 10 were ethylene oxide adducts of a mixture of amines which principally covers the range of C 1-uHu- INH: where the number of ethylene oxide units per amine is 15 and 25, respectively. (4) Surfactants Nos. 11 and 12 were a coco-amine ethylene oxide adduct, and a stearyi-amine ethylene oxide adduct, respectively. The farmer's structure is (C H: C H10) ,H

in which ..+y=15; the latter has the same structure except that z+y=50 (5) Surfactant No. 13 was a commercially available product, a dehydroabletylamine ethylene oxide adduct with the structure in which z+y=20. (6) Surfactant No. 18 was sodium p-t-octylphenoxypolyethoxy (20 units) acetate with the structure R0(cH,cn,0) ,ocntcoom.

e Same as footnote 8 in Table 1. b Same as footnote b in Table 1. Same as footnote 0 in Table 1. in The Venture crude 011 contains some impurities which were extracted into the aqueous phase in some 1ns oes.

I Same as footnote 0 in Table 1.

TABLE 3.EMULSIFIED IN CAUSTIC, BROKEN WITH ACID; SURFACTANT RECOVERED AS PRECIPITATE [Organic phase: Toluene (except for item marked by asterisk in which Venture crude oil was used). Aqueous phase: 0.5% surfactant, 0.5% NaOH, deionized water] Emulsion Emulsion Percent of Percent of Percent of Suriacinstability Material instability pH after LC. in 1.0. in LC. which that in caustic added aiiticr acidiacidification aqueous toluene precipitated cation 11:504.--. 100 2.1 H:SO 100 2.4 H1304.-- C8. 100 4.0 H,SO 92 4 NOTES ON TABLE 3 (1) Surfactant No. 1 was disodium B-taiiow iminodipropionate. (2) Surfactant No. 2 was disodium fi-lauryl iminodipropionate. (3) Surfactants Nos. 3 and 4 were sodium B-coco amino-propionate.

I Same as footnote a in Table 1. b Same as footnote d in Table 2.

I TABLE 4.EMULSIFZED 1N son) BROKEN wrrn BASE; sunno'rsn'r RECOVERED IN AQUEOUS OR onosmo rmsn [Organic phase: Toluene (except for items marked by asterisk in which Venture crude oil was used). Aqueous plmse: 0.5% suriectant, 0.6% H180 deionized water (all pH's: 1-2)] Emulsion Emulsion pH alter Percent: Percent of Surfac- Mole ratio of instability Material instability adding 1.0. in L0.- m tent E061) in acid added after adding Materiel aqueous toluene material 5 i 101) 5 0 NsOE 78 lL-i 23 5 100 NaO 11.4 4 90 5 0 NaOH.. 100 23.2 30 7. 5 100 7.5 0 NnOE-. 82 11.6 $8 20 9 NaOH... 25 10 L8 NsOH-- 83 .13. 3 12 18 NsOH-- 102 12.7 108 l8 NOTES ON TABLE 4 (l) The results with surfactants l to 6 inclusive show the diflerent efiects with difierent oils. Note that with Venturn crude oil the same surfactant that worked well in Nos. 2 and 4 did not work at all with toluene in Nos. l and 3. Similarly, with Venmra crude oil in No. B, a good result was obtained, but in No. 6 toluene did not work at all.

s Same as footnote 8 in Table 1.

In the ernmples shown in Tables 1 to 4, the number phase in the case of toluene) was withdrawn and armof units of ethylene oxide employed in the amine-E0 adducts therein specified ranged from 10-30 in some cases andirom 15-50 in others. Actually, these are Examples of Process Employing Continuous Cycles from the foregoing tables, it was apparent that among the surfactants which may be employed in the inventive process, one of the most successful types is the group comprin'ng a number of amine-ethylene oxide adducts. Of those, the products, identified as an ethylene oxide add-not (15-30 units) of a commercial product comprislog a mixtum of amines which principally covers the Yangfi i-QnHgNHa to 141417139: excelled all other surfactants tested in several oil-water systems when com sideration was given to emulsion stability in caustic solution, efficiency (time and completeness) of breaking, and tecoversbility of the surfactant. One of them (the one having 15 units of ethylene oxide) was therefore selected for a scries'of recycling experiments in which the same batch of caustic-surfactant solution was used repeatedly to form the emulsion, then reclaimed, freed of most of the inorganic salt, and used again to emulsify a fresh batch of the some oil. The number of cycles .in such experiment was limited only by the fact that the volume of emulsion was constantly being decreased as samples were removed for determination of emulsion stability in caustic solution and for analysis. This type of limitation will vary, depending upon the scale on which my invention is practiced, any samples needed during the process, etc., if no makeup surfactant is used.

The results obtained with the recycling process are set forth in Tables 5 to 8. They were obtained by the following procedure:

Equal volumes of oil and of a 0.5 percent caustic- 0.5 percent surfactant solution (500 cc. of each phase at the start) were vigorously mixed by a mechanical shaker for 15 minutes. A control sample of the emulsion was withdrawn for measuring emulsion stability in caustic, a lowed to stand for an hour, and the phase volumes read. The remaining emulsion was poured into a graduated separatory funnel and dilute H 80 added until the emulsion broke and the pH was below 5, shaking well after adding each increment. The completeness of breaking (i.e., percent recovery of oil) was determined.

A sample of the aqueous phase (and of the organic lyzed for surfactant. An amount of Ca(OH), equivalent to the H present was added to the solution. The solution was shaken for a few minutes, then filtered to remove the precipitate. A sufficient amount of NaOHwasthenaddodtoraiseihepHtothatofmc starting solution, viz., 12.8-42.9.

Failure to remove CaSO; prior to replenishing caustic would result in the redissolving of some 0e50,, and such removal is, therefore, preferable. (If other alkaline materials are used in lieu of the Ca(0H)=, this problem need not occur. Optionally, also, HCl {or any other inorganic acid, or organic acid, or acid salts] could be used instead of H2 4. and other alkaline materials can also be used. The i-ICI and NaOH will form NaCl which can be allowed to accumulate or may be removed by some other means without interfering with the proccss.) The Cowl-l), precipitated by the NaOH was eliminated by refiltration. The volume of the filtrate was measured and an equal volume of fresh oil added thereto, after which all of the foregoing steps were repeated 3. number of times as shown in Tables 5 to 8.

The cyclic process is typically represented in the diagram shown in the attached drawing which illustrates an application-of my invention to oil recovery from pe troleum-bearing formations. The drawing shows, in outline fashion, a flow diagram" of oil recovery via wells employing the process of my invention.

as aforesaid.

TABLE 5.TOLUENE Emmi. Oumn- Cum. Emu]. pH instsb. Percent latlve. Percent Percent Cycle lustsb. after alter oi Percent 0! 1.0. of

N o. in ncldlllncidlll- LC.- 0! in LG.

control cation cation in 21:0 1.0. tol. in

tol.

40 2. 9 (102. 6) (I02. 6) (0. 6) (0. 6) 51 2 l 101 99. 3 102. 2 0 0. 6 39 Z 6 mo 98. 0 100. 3 0 0. 6 28 2. 2 100 98. 5 N. 7 0. 6 l. 2 50 2. 4 100 100. 8 99. 4 3. 8 5. [l 50 2. 8 97. 8 97. 0 0. 6 5. 7 49 2. 7 101 101. 0 98. 0 0. 7 5. 0 64 2. 2 102 100. 0 08. 0 2. 9 7. 8

. I.C." is initial concentration Table 6.-VENTUBA CRUDE OIL Emu}. pH alter Percent oi Cumula- Cycle No lnstsb. in acidifice- LC. in tive percent control tion H4O oi LC I I.C." is inltisl concentration TABLE 7.HOWARD GLASSCOCK CRUDE OIL Emu] pH altar Emul. Percent oi Cumula- Gycle Instab in acidiflciv tab. LC.- in atlve per- No. in control tion after acidl- H 0 cent 0! I C flcation 64 8. 0 (96) (96) 96 2. 8 100 99 95 0 3. 4 80 99 94 88 3.0- 91 100 94 72 2. 8 94 90 86 54 2. 7 94 93 79 a 2.3 10s as 14 l I.C." is initial concentration.

ElABLE B.--HAWKINS FIELD CRUDE OIL Emul pH after Emu] Percent o! Cumula- Cycle Instab. in scidifica- Instab 1.0.- in ative per- No. in control tlon after acidl- H=0 cent 0! LC.

ncstion 30 3. 1 (93) (89) 84 3. l. 95 89 as 2. 6 97 I) 71 63 2. 3 80 89 63 46 2. 87 91 67 100 2. 7 99 as 66 60 2. 7 82 W 50 50 2. 4 88 94 47 l 1.C." is initial concentration.

Some of the more salient points reflected by the recycling data in Tables 5 to 8 may be summarized as follows:

Average Percent Recovery of Aqueous Phase Average Percent Recovery of Surfactant into Aqueous Phase Toluene 100 Ventura 94 Glasscock a 94 Hawkins 91 Conclusions and Observations The foregoing description has clearly demonstrated the efiicient manner in which my invention can be employed in connection with the recovery of oil by such common practices as the drilling of adjacent holes deep into the ground, then injecting a flushing material into one hole to force the oil out of another. In the past, water containing a surfactant was used for this flushing op 'eration. Then a more recent devdopment invoived the use of a mixture of a 'surfactaut such as t-octylphenol ethylene oxide adduct and a caustic solution. This flushing procedure emulsified oils which were contained in petroleum-producing formations, and the like, which could not be broken loose and flushed out by pie-existing procedures. A detailed explanation of this procedure can be found in US. Patent 2,882,973.

The major obstacles to widespread use of this last procedure have been the difliculty and expense involved in breaking the emulsion thus formed, plus the fact that the surfactant has not been recoverable. My invention has overcome this objection and now makes it possible to employ this eflicient and economical technique for the recovery of many billions of gallons of oil which heretofore were relatively inaccessible from a commercial standpoint.

I claim:

1. The process of recovering oil from an oil-bearing formation which comprises introducing thereunto through an injection well an alkaline aqueous solution of a pH- sensitive surfactant so as to form an oil-water emulsion in the well, the surfactant being selected from the class consisting of (a) the ethylene oxide adducts of a range of amines represented by the formula C, H NH, where the number of ethylene oxide units is from 5 to 50 per amine;

C =J-I e NH(C H O) SO Na where "=3 to 50; and

)IH RN\ :HiO), in which R is a dehydroabietyl group and x+y=15 to 50,

collecting the oil-water emulsion which issues from said well, and adding to the emulsion an acidic substance so as to make the oil-water system acidic and thereby concentrate the surfactant in a bulk phase where it is available ftigiurther use, while concentrating the oil in another p 2. The process of recovering oil from an oil-bearing formation which comprises introducing thereunto through an'injection well an acidic aqueous solution of a pH- sensitive surfactant so as to form an oil-water emulsion in the well, the surfactant being selected from the class consisting of (a) the ethylene oxide adducts 05 a range of amines represented by i116 formula C11 HMNHI WhCXC the number of ethylene oxide units is from 5 to 50 per amine;

50; and

(C'sHI hH References Cited in the file of this patent UNITED STATES PATENTS while concentrating the oil in an- 2,288,857 Subkow July 7, 1942 2,662,062 Sumerford Dec. 8, 1953 2,882,973 Doscher Apr. 21, 1959 OTHER REFERENCES The Chemistry of Fatty Amines, published by Armour & Co., 1948, pp. 1-5, 17, and 18.

a bulk phase where it is avail-- 

1. THE PROCESS OF RECOVERING OIL FROM AN OIL-BEARING FORMATION WHICH COMPRISES INTRODUCING THEREUNTO THROUGH AN INJECTION WELL AN ALKALINE AQUEOUS SOLUTION OF A PHSENSITIVE SURFACTANT SO AS TO FORM AN OIL-WATER EMULSION IN THE WELL, THE SURFACTANT BEING SELECTED FROM THE CLASS CONSISTING OF (A) THE ETHYLENE OXIDE ADDUCTS OF A RANGE OF AMINES REPRESENTED BY THE FORMULA C11-24H23-49NH2 WHERE THE NUMBER OF ETHYLENE OXIDE UNITS IS FROM 5 TO 50 PER AMINE; (B) C11-24H23-49NH(C2H4O)NSO4NA WHERE N=3 TO 50; AND (C) 